1. Field of Invention
The present invention is related to a developing device and an image forming apparatus having the developing device such as a laser printer.
2. Description of Related Art
In a laser printer disclosed in U.S. Pat. No. 6,041,203, a developing cartridge storing toner is detachably mounted in the printer. The developing cartridge includes a toner box for storing toner and a developing roller for bearing a thin layer of toner. An agitator is arranged in the toner box for agitating and transporting the toner.
A supply roller is arranged in the developing cartridge for supplying the toner that is transported from the agitator to the developing roller. The agitator, the supply roller and the developing roller are arranged rotatably.
The developing cartridge further comprises a gear mechanism for transmitting driving force to the developing roller, the supply roller and the agitator.